P V T Gas Laws.

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Presentation on theme: "P V T Gas Laws."— Presentation transcript:

2 Learning ObjectivesTLW know the variables that influence the behavior of gases (TEKS 9)TLW be able to describe interrelationships between temperature, number of moles, pressure, and volume of gases in an enclosed system (TEKS 9.A)TLW perform stoichiometric calculations to determine mass and volume relationships between reactants and products involving gases (TEKS 9.B)TLW describe the postulates of kinetic molecular theory (TEKS 9.C)

3 I. Gas Laws A. Four properties of gases 1. Volume - V 2. Pressure – Pgases do not have a defined volumeparticles of a gas expand to fill their containervolume is measured in L (liters)2. Pressure – Pcollisions of particles with a surfaceP measured in atm, kPa, torr, mm Hg

4 3. Temperature – To 4. Quantity – nthe measure of average particle speedgas particles are in constant motionTo for gases are measured in K (Kelvin)4. Quantity – nmeasure of how much there is of a gasMOLES!!!!!22.4 L of gas = 1 mole

5 Postulates of Kinetic Molecular TheoryGases are composed of a large number of particles that behave like hard, spherical objects in a state of constant, random motion.These particles are much smaller than the distance between particles. Most of the volume of a gas is therefore empty space.There is no force of attraction between gas particles or between the particles and the walls of the container.These particles move in a straight line until they collide with another particle or the walls of the container.Collisions between gas particles or collisions with the walls of the container are perfectly elastic. None of the energy of a gas particle is lost when it collides with another particle or with the walls of the container.The average kinetic energy of a collection of gas particles depends on the temperature of the gas and nothing else.

6 Postulates of Kinetic Molecular TheoryCheck out this interactive tool which demonstrates the postulates in action

7 B. Gas laws are based mathematically. on the relationship of the fourB. Gas laws are based mathematically on the relationship of the four properties of gasvolumepressuretemperaturequantity

8 II. The Gas Laws (4 major ones)A. Boyle’s Law1. Discovered that gas pressure and volume are related2. If pressure is increased then volume decreases3. Pressure and volume are inversely related4. Meaning = whatever pressure does volume does the opposite

12 5. Example of Boyle’s LawA sample of gas has a volume of 4.2 L and a pressure of 0.95 atm. If the pressure on the balloon increases to 1.90 atm what will the new volume be?0.95 atm1.90 atm4.2 LP1V1 = P2V2V = ?(.95 atm)(4.2L) = (1.90 atm)V2V2 = 2.1 L

13 B. Charles’ Law1. Discovered the relationship between volume and temperature2. If To increases then the volume increases3. To and volume are directly proportional4. Meaning = whatever volume does To does the exact same thing

18 5. Example of Charles’ LawAnother sample of gas has a volume of 2.0 L and a To of 100 oC. If the To is increased to 200 oC, what will the new volume be?V = 2.0LV = ?100ºC200ºCV1/T1 = V2/T22.0L/(100 oC + 273) = V2/(200 oC + 273)V2 = 2.54 LKELVIN!!!!!!!!

19 C. Gay-Lussac’s Law1. Discovered the relationship between Pressure and To2. If To increases then Pressure increases3. To and P are directly proportional4. Meaning = whatever To does pressure does the exact same thing

21 Example of Gay-Lussac’s LawAnother sample of gas has a volume of 2.0 L a To of 25 oC, and a pressure of 2.00 atm. If the To is increased to 75 oC, what will the new pressure be?25ºC2.00 atmV = 2.0L75ºCV = 2.0LP = ?P1/T1 = P2/T22.00 atm/(25 oC + 273) = P2/(75 oC + 273)P2 = 2.34 atm

22 D. Avogadro’s LawIf pressure and temperature are kept constant, the volume of a gas is directly proportional to number of moles of a gasThis is why a balloon gets larger as you blow it up… not the pressure1 mole of gas = 22.4 LMathematically speaking…..V1 = V2n1 n2

23 Example of Avogadro’s LawI have a balloon with 0.25 moles of air in it and its volume is 0.30 L. If I blow it up more to 0.75 L, how many moles have I added of air? V1/n1 = V2/n L = 0.75 L = 0.63 moles 0.25 moles n2 moles

34 Dalton’s Law of Partial PressureSum of the pressures of each gas equals total pressure of systemP1 + P2 + P3 + …. + Pn = PtotalA gas is 48% O2 & 52% N2. Total pressure is 100 kPa. What is the pressure of each gas?100(.48) = 48 kPa for O2 and 100(.52) = 52 kPa for N2